1. Field of the Invention
This invention relates to polyaza caged molecules having the hexaazaisowurtzitane caged ring system, including one with nitro groups attached to each nitrogen atom, and a method for producing the same, useful as an explosive. More particularly, the invention relates to an improved method of debenzylating 4,10-dibenzyl-2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane derivative and the subsequent nitrolysis thereof to produce 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW).
2. Description of the Related Art
Known polynitramines such as 1,3,5-trinitro-1,3,5-hexahydrotriazine (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) are high-energy, high-density explosive compounds (R. Meyer, “Explosives,” Third edition, VCH Publishers, Weinheim, Germany, 1987). They can be prepared by nitrolysis of hexamine with nitric acid and other similar procedures. Stable polynitramines having energy and density greater than that of HMX were unknown until the synthesis of a new class of explosives described as caged polynitramine was disclosed in the application by Arnold T. Nielsen on Sep. 30, 1988.
Nielsen started with benzylamine and glyoxal which are condensed in a suitable solvent in the presence of a catalyst to produce hexabenzylhexaazaisowurtzitane (HBIW). The hexabenzylhexaazaisowurtzitane (HBIW) was reductively acylated in the presence of a catalyst in a second step to produce dibenzyltetraacetylhexaazaisowurtzitane (TAIW).
The Nielsen method involved treating 4,10-dibenzyl-2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (TAIW) with nitrosonium tetrafluoroborate in sulfolane to form 4,10-dinitroso-2,6,8,12-tetraacetyl-2,4,6,8,10,12-hexaazaisowurtzitane (TAIW(NO)2). The 4,10-dinitroso-2,6,8,12-tetraacetyl-2,4,6,8,-10,12-hexaazaisowurtzitane (TAIW(NO)2) in turn was treated with nitronium tetrafluoroborate in sulfolane to give the explosive, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW). These flouroborate reagents are very expensive and, additionally, disposal of left-over waste is very costly because of the presence of fluoride.